The present disclosure relates generally to time division duplex (TDD) communication systems, and more particularly to receiver protection in the TDD transceivers.
TDD is a process of allowing two way communications between two devices by time sharing. When using TDD, one device (device A) transmits, then the other device (device B) listens for a short period of time. After the transmission is complete, the devices reverse their roles, i.e., device A becomes a receiver and device B becomes a transmitter. The process continually repeats itself, so that data appears to flow in both directions simultaneously.
A circulator is usually used to switch connections of either the transmitter or receiver to a common antenna. A circulator passes a transmit signal to the antenna with low attenuation, but will not pass the transmit signal to the receiver. A limitation to using a circulator in a TDD system is that any transmit power reflected by the antenna, i.e., not absorbed by the antenna, may be conducted back to the receiver. This may damage the receiver. The receiver, in turn, must therefore increase power handling capability.
Therefore, what is desired is a protection circuit for the TDD receiver.